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T. A. EDISON.

PROCESS OF DUPLIGATING PHONOGRAMS. No. 382,419.

Patented May 8, 1888.

N, PETERS. i'llow-Lilllugnphur. Washinglun. 0.0)

NITED STATES PATENT Quince.

THOMAS A. EDISON, OF LLEWELLYN PARK, NEW JERSEY.

PROCESS oF DUPLICATIN'G PHONOGRAMS.

SPECIFICATION forming part of Letters Patent No. 382,419, dated May 8, 1888.

Application filed March 8. 1888.

Serial No. 266,596. (No model.)

The object of my invention is to produce a.

simple and efficient process for duplicating phonographic records. In applications already filed by me I describe a process for duplicating phonograins, wherein a metallic matrix is formed by depositing metals-over the surface of cylindrical wax phonograms and then dissolving out the wax, leaving a hollow matrix br mold with the record in relief upon its inner surface. By my present invention I propose to apply the process of knurling to the duplication of phonograms as distinguished from molding. 1,644 of 1878 I proposed to construct a knurl by depositing metal over the record; but it is obvious that if this deposit were made of any thickness at all the record would be largely obliterated.

By my present invention I deposit metals over the record of the recordingsurface of a cylindrical wax phonogram, and after melting out the original wax I divide the remaining cylinder by splitting it longitudinally wit-h a thin saw on one side. I then open the cylinder out flat or further bend it into the form of a cylinder, with the record upon its exterior. To give the necessary strength I provide a suitable backing. Ihe result is a flat or cylindrical knurlingsurface having the record in relief, so that by rolling a wax phonogramblank upon it the original record will be reproduced.

For making the first deposit upon the original wax phonogram I prefer to emplgysw",

which is deposited upon the wax phonogram by the vacuumv process or by electroplating. A thin coating is produced in this way, which is backed up by a coating of lead or tin, which is also quite thin. For example, it may be one-sixteenth of an inch in thickness. The silver gives an inoxidizable surface, which is cheaper than gold or platinum. After the wax is dissolved out and this cylinder split on one side it will be found to have sufficient flexi- In my English Patent No;

bility by reason of the materials employed and the thinness of the cylinder to permit of its being bent without injury to the record into the form of a fiat sheet or a reversed cylinder.-

be employed, or materials other than wax.

In the accompanying drawings, forming a part hereof, Figure 1 is a sectional view showing the original phonogram with the deposit thereon; Fig. 2, a similar view with the original phonogram melted out or removed from the encircling metal deposit. Fig. 3 is a sectional View illustrating the flat knurling-surface, and Fig. 4 a similar view illustrating the cylindrical knurling-surface.

A is the original wax phonogram, upon the surface of which is the phonographic record, upon which is formed a thin deposit of silver, a, and over this a thicker deposit of lead or tin, I), the entire metallic deposit being, for illustration, one-sixteenth of an inch thick.

After this deposit is made the wax cylinder A i is melted out of the metal coating, leaving the metallic cylinder B (shown in Fig. 2) with the record in relief upon its inner surface. This cylinder B is split longitudinally on one side at the point 0, and it is then bent out flat and mounted upon asuitablebaseplate, G, to which it is secured by cement, forming a flat knurling-surface, D; or the cylinder B may be bent reversely over a solid cylinder, E, and secured thereto by cement, forming a cylindrical knurl, F. (Shown in Fig. 4.) The wax duplicate phonogram blank G is impressed with the original record by rolling it against the flat or the cylindrical knurling surface, as will be readily understood.

I do not claim herein the method of dupli eating phonograms by depositing metals upon a cylindrical wax phonogram and then melting or dissolving out the original wax phonogram, leaving a matrix with the'reco'rd in relief upon its inner surface; neither do I claim lOC herein the use ofa vacuum deposit for pro-J ducing a coating upon the wax phonogram; neither do Iclaim herein a duplicate phonogram constructed of a hard material not capable of being satisfactorily indented by a phonograph, since these features are covered in my applications Nos. 743, 744, and 751, already filed by me. Such applications have respectively the Serial Nos. 259,895, 259,896, and 262,428.

What I claim as my invention is 1. The process of duplicating phonogranis, consisting in forming a knurl having the original record in relief by depositing metal upon the original record, removing the original phonogram and opening the metallic coating, and then impressing duplicate phonogramblanks with the original record by means of such knnrl, substantially as set forth.

THOS. A. EDISON.

Witnesses:

WM. PELZER, E. C. ROWLAND. 

